Surface recombination of hexagonal GaN crystals

The influences of the surface recombination on the emission properties of the freestanding GaN with different polarity (+c and –c orientations) and forms were investigated. The time‐resolved photoluminescence measurements for the GaN pieces fabricated by cleaving the substrate indicated that the increase in surface/volume ratio leaded to the increase in the surface recombination rate even at low temperature. The excitation power density dependent photoluminescence measurements on as‐received and buffered hydrofluoric acid treated c ‐plane GaN surfaces indicated that the surface band bending was closely related to the surface recombination processes. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)